Reflectance Spectroscopy (RS)
In the analysis of polychrome artworks, among the techniques available in the portable version, Reflectance Spectroscopy (RS) has been established as a powerful one for the identification of pigments. An RS spectrum shows for each wavelength, the ratio between the intensity of the reflected light and the incident light, measured with respect to a standard white reference. This ratio is called reflectance and is given in percentage (%). The RS spectra can provide information useful for pigments identification since the radiation that is not reflected is absorbed or transmitted depending on the chemical composition of the material tested. The peculiar advantage of this method with respect to the other spectroscopies most commonly used, such as XRF and Raman, is that the RS equipment can be assembled with relatively low-cost components.
